sknight_cooVersion

#include<bits/stdc++.h>
#define mp make_pair
#define x first
#define y second
using namespace std;
void cass(){ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    freopen("sknight.inp", "r", stdin);
    freopen("sknight.out", "w", stdout);
}

const int B = 1e6 + 1;
const int HB = 1e3 + 1;
const int N = 1001;

long long tx[10] = {0, -1, 1, 1, -1, -1, -1, 1, 1};
//int tx[10] = {0, -2, -2, 2, 2, -1, -1, 1, 1};
//int ty[10] = {0, -1, 1, -1, 1, -2, 2, -2, 2};
long long ty[10] = {0, -1, 1, -1, 1, -1, 1, -1, 1};

long long k, l;
int xt, yt;
int n;
pair<int, int > ban[N];

void init(){
    k--; l--;
    for (int i = 1; i <= 4; i++){
        tx[i] *= k;
        ty[i] *= l;
    }
    for (int i = 5; i <= 8; i++){
        tx[i] *= l;
        ty[i] *= k;
    }

}

int deg[2 * HB][2 * HB];
int tab[2 * HB][2 * HB];

void sub2(){
    for (int i = 1; i <= n; i++) tab[ban[i].x + HB][ban[i].y + HB] = 1;
    queue<pair<int, int > > Q;
    Q.push(mp(xt + HB, yt + HB));
    memset(deg, -1, sizeof(deg));
    deg[xt + HB][yt + HB] = 0;
    while (!Q.empty()){
        pair<int, int > pre = Q.front(); Q.pop();
        for (int t = 1; t <= 8; t++){
            int nx = pre.x + tx[t];
            int ny = pre.y + ty[t];
            if (1 <= nx && nx <= 2001 && 1 <= ny && ny <= 2001 && deg[nx][ny] == -1 && tab[nx][ny] == 0){
                deg[nx][ny] = deg[pre.x][pre.y] + 1;
                Q.push(mp(nx, ny));
                if (nx == HB && ny == HB){
                    cout << deg[nx][ny];
                    exit(0);
                }
            }
        }
    }
    cout << -1;
}

int naive(int fixedx, int fixedy){

    queue<pair<int, int > > Q;
    Q.push(mp(fixedx , fixedy ));
    memset(deg, -1, sizeof(deg));
    deg[fixedx ][fixedy ] = 0;
    while (!Q.empty()){
        pair<int, int > pre = Q.front(); Q.pop();
        for (int t = 1; t <= 8; t++){
            int nx = pre.x + tx[t];
            int ny = pre.y + ty[t];
            if (0 <= nx && nx <= 2 * HB && 0 <= ny && ny <= 2 * HB && deg[nx][ny] == -1){
                deg[nx ][ny] = deg[pre.x][pre.y ] + 1;
                Q.push(mp(nx, ny));
                if (nx == HB && ny == HB){
                    return deg[nx][ny];
                }
            }
        }
    }
    return -1;
}

int numPre = 0;

pair<int, int > prepare(){
    long long inf = 1e15 + 6;
    // go from xt, yt (haved fixed) to the 1..2001 x 1.. 2001 field
    long long curX = abs(xt), curY = abs(yt);
    while (1){
        if ( - HB <= curX && curX <= HB && - HB <= curY && curY <= HB) return mp(curX + HB, curY + HB);
        long long minDis = inf;
        long long minIdX {}, minIdY{};
        for (int t = 1; t <= 8; t++){
            long long nx = curX + tx[t];
            long long ny = curY + ty[t];
            if ((nx) * (nx) + (ny) * (ny) < minDis){
                minDis = (nx) * (nx) + (ny) * (ny);
                minIdX = nx;
                minIdY = ny;
            }
        }
        curX = minIdX;
        curY = minIdY;
        numPre++;
    }
}

void full(){
    pair<int, int > stpoint = prepare();
    int tmp = naive(stpoint.x, stpoint.y);

    //if (tmp != -1)
        cout << numPre + tmp;
}

int main(){
    cass();
    cin >> k >> l;
    cin >> xt >> yt;
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> ban[i].first >> ban[i].second;

    init();

    if (n){
        sub2();
    }
    else full();
}